The invention relates generally to electrical heaters, and more particularly to thermistor controlled heaters, for example those having a positive temperature coefficient material.
Electrical heaters having a thermistor layer interconnecting electrodes disposed on a dielectric material are known generally, as disclosed for example in U.S. Pat. No. 4,857,711 entitled xe2x80x9cPositive Temperature Coefficient Heaterxe2x80x9d and in U.S. Pat. No. 4,931,627 entitled xe2x80x9cPositive Temperature Coefficient Heater With Distributed Heating Capabilityxe2x80x9d, both of which are assigned commonly with the present application.
An object of the present invention is to provide in some embodiments thereof novel electrical heaters that overcome problems in and improve upon the prior art.
Another object of the invention is to provide in some embodiments thereof novel electrical heaters that are economical and reliable.
A further object of the invention is to provide in some embodiments thereof novel electrical heaters having the capacity for providing more uniformly heated surfaces.
It is also an object of the invention to provide in some embodiments thereof novel electrical heaters having zones with more or less heat.
Another object of the invention is to provide in some embodiments thereof novel electrical heaters having electrodes with opposite end portions located at a common termination zone, for example at a common comer of the heater or along the same side thereof.
Another object of the invention is to provide in some embodiments thereof novel electrical heaters formed on a single substrate.
A further object of the invention is to provide in some embodiments thereof novel electrical heaters having multiple temperature configurations or settings.
A further object of the invention is to provide in some embodiments thereof novel electrical heaters having multiple temperature configurations or settings without complex or costly electrical controls.
Yet another object of the invention is to provide in some embodiments thereof novel positive temperature coefficient electrical heaters having multiple temperature settings controlled by a switch.
Another object of the invention is to provide in some embodiments thereof novel electrical heaters suitable for use in seat heating applications.
A more particular object of the invention is to provide in some embodiments thereof novel electrical heaters comprising first and second electrodes disposed on a substrate in spaced apart relation, adjacent portions of the first and second electrodes having interdigitated electrode portions protruding therefrom, other adjacent portions of the first and second electrodes devoid of interdigitated electrode portions, a thermistor material electrically interconnecting the first and second electrodes, a summation of electrical paths along the first and second electrodes from corresponding electrical power application end portions thereof to adjacent portions of the first and second electrodes is substantially the same.
Another more particular object of the invention is to provide in some embodiments thereof novel electrical heaters comprising first and second electrodes disposed on a substrate in spaced apart relation, the first and second electrodes each having opposite end portions located at a common termination zone on the substrate, adjacent portions of the first and second electrodes having interdigitated electrode portions protruding therefrom, a thermistor material electrically interconnecting the first and second electrodes.
A further more particular object of the invention is to provide in some embodiments thereof novel electrical heaters comprising a plurality of first, second and third electrodes disposed on a substrate in spaced apart relation, the second electrode located between the first and third electrodes, the first, second and third electrodes each having opposite end portions located at a common termination zone of the substrate, a thermistor material electrically interconnecting the first, second and third electrodes.
Yet another more particular object of the invention is to provide in some embodiments thereof novel electrical heaters comprising first and second electrodes disposed on a substrate in spaced apart relation, a spacing between some adjacent portions of the first and second electrodes is different than a spacing between other adjacent portions of the first and second electrodes, a thermistor material electrically interconnecting the first and second electrodes, a summation of electrical paths along the first and second electrodes from corresponding end portions thereof where electrical power is applied to adjacent portions of the first and second electrodes is substantially the same.
These and other objects, aspects, features and advantages of the present invention will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators.